WORCESTER — The quick work of a police officer aided by two good Samaritans on bicycles led to the arrest of a 51-year-old man shortly after he allegedly robbed the Gulf Gas Station in Kelley Square early Tuesday morning.

The officer was on patrol about 1 a.m. when he noticed three men on bicycles pedaling very fast away from the gas station.

Just as he was pulling into the business, the clerk ran out and yelled to the officer that one of the men had just robbed him. The clerk also told the officer that the two men were chasing the suspect, also on a bicycle.

The two men chasing the suspect pointed the officer in the right direction, according to police. The officer caught up to the suspect at Washington and Lamartine streets.

David Cardona, 51, of 260 Pleasant St., was placed under arrest. A search of Mr. Cardona produced evidence that linked him to the Gulf robbery, according to police.

There were no weapons on Mr. Cardona, although he allegedly told the clerk he had a knife on him.

The clerk had apparently witnessed Mr. Cardona stuffing items into his jacket. He confronted him.

"The clerk attempted to grab Cardona but he reached into his jacket pocket and threatened the clerk verbally that he had a knife," according to a Worcester Police news release. "The clerk let go and Cardona fled on the bike."

Mr. Cardona was charged with assault with a dangerous weapon, armed robbery and intimidation of a witness.